The present invention generally relates to the storage of body fluids. More specifically, the present invention relates to the storage and use of blood and its components.
It is, of course, known to use blood and other body fluids in a number of medical procedures. Blood transfusions are an example of such procedures. Blood is collected from a donor and can be transfused into a recipient.
Blood after being received from a donor is stored, typically, in flexible plastic containers until use. Blood can either be housed and stored in a container as whole blood or broken down into its individual components, e.g., plasma, buffy coat layer, and packed red cells. For example, it is known to separate whole blood either through a centrifuge process or a process such as that disclosed in U.S. Pat. Nos. 4,350,585 and 4,608,178 into plasma, buffy coat, and packed red cells.
In a great majority of cases, blood is stored for a number of days and not immediately infused into a recipient. In most situations, the blood components are separately stored. For example, it is known to separately store and utilize the red blood cell component of whole blood.
In order to maintain the viability of red blood cells and other blood components, it is necessary to provide a storage solution. For example, the storage solution provides an energy source for the red blood cells.
Such storage solutions typically include a sugar component, such as glucose, as well as other components, such as, e.g., sodium citrate, sodium bisphosphate, sodium phosphate dibaSic, adenine, and mannitol. One of the difficulties encountered with storage solutions is during the sterilization of the solution. Glucose is known to degrade under autoclaving (heat) sterilization 10 conditions unless maintained in an acidic medium. If glucose is not in an acidic medium, when heated, glucose will caramelize.
However, it is considered as an advantage for storage solutions to be formulated at a pH as close as possible to the physiological pH of blood (pH 7.4) in order to better maintain red cells properties. Therefore, a problem that has been encountered is the sterilization of storage solutions containing dextrose and buffered at a neutral pH.
Other fluids that may be added to blood or a blood component may also raise stability and sterilization issues if provided in the container that will store the blood component. For example, as set forth in U.S. patent application Ser. No. 07/952,427 entitled: "STEAM STERILIZABLE SYSTEM FOR INACTIVATING VIRAL CONTAMINANTS IN BODY FLUIDS", methylene blue (3-7bis(dimethyl amino phenothiazine-5-ium chloride), a viral inactivation agent, may leach into certain plastics if heated.
As set forth in that patent application, if methylene blue is placed in a standard blood pack unit constructed from polyvinyl chloride (PVC) under standard conditions and the unit is then sterilized, at least a portion of the methylene blue migrates into the PVC layer reducing the methylene blue present. The specific amount of methylene blue that migrates is variable depending on conditions. However, a precise amount of methylene blue may be maintained during sterilization when it is contained in an elongated tube whose inside layer or total layer is made of a non-PVC material. Envisioned methods of using methylene blue to treat blood and other body fluids require that precise amounts of methylene blue be used. Plastics such as PVC, however, may exhibit desirable characteristics for storing blood or its components.
Of course, one of the issues in transfusing blood into a patient is insuring that the blood is compatible with the patient's blood. For example, it is known to insure that similar blood types are infused into the patient. In order to type or match the blood, it is necessary for a sample of blood to be accessed and tested so as to determine the type and other characteristics of the blood or component.